Size 45 x 85 x 20 mm - weight 19 grams Manganese Pseudomorph Oxides Psm Gypsum Among the most famous European pseudomorphs there are definitely Lavrion's manganese oxide perimorphs after gypsum. These specimens consist of an oxide coating of gypsum crystals, which afterwards dissolved and left hollow manganese-rich tubes and channels in the gossan matrix. A pitch black manganese oxide coating had covered and partially replaced a group of elongated gypsum crystals. This very interesting process was delayed in some places, and the white crystals of Gypsum are still visible With acrylic support base, note the base if you don't like it, remove it very easi will be sent with a security number